Generally, a traveling mower includes a mower unit mounted to a traveling body to be movable up and down, and a grass collection box having a front opening communicating with a discharge duct extending rearward from the mowing unit. An example of such traveling mower is disclosed in JP-A-2001-45829. The disclosed mower includes a grass collection box which is pivotable for switching between a grass collection posture for receiving the mowed turf grass and a discharge posture for discharging the collected turf grass.
In the conventional traveling mower, the switching of the posture of the grass collection box is performed by the driving of a hydraulic cylinder mounted on the traveling body. The hydraulic system including a hydraulic pump and a hydraulic pipe has a complicated structure and increases the number of parts, which leads to an increase in size and manufacturing cost of the mower. Further, by the hydraulic driving, the posture of the grass collection box cannot be changed smoothly when the grass collection box is empty or substantially empty although the weight of the grass collection box in such a state is small.
As compared to the above, a structure designed to manually change the posture of the grass collection box is advantageous in that the mechanism for turning the grass collection box can be simplified.
However, when the mechanism is so designed that the posture of the grass collection box is changeable by the application of an operational force corresponding to the rotation load of the grass collection box in the empty or substantially empty state, the posture change of the grass collection box in the state of containing much turf grass requires a large operational force, and the turning operation becomes a burden on the operator. On the other hand, when the mechanism is so designed that the posture of the grass collection box is changeable by the application of an operational force corresponding to the rotation load of the grass collection box in the state of containing much turf grass, the grass collection box in the empty or substantially empty state turns easily and largely changes its posture even by the application of a small operational force so that the impact due to the posture change is large. In this way, the conventional structure for manually changing the posture of the grass collection box has a drawback that the operational force for changing the posture cannot be adjusted correspondingly to the presence or absence of turf grass or the amount of turf grass.
It is, therefore, a first object of the present invention to solve the above-described problems and provide a traveling mower which has a simple structure and is capable of reliably adjusting the operational force for the posture change of the grass collection box depending on the presence or absence of turf grass or the amount of turf grass in the grass collection box.
To reduce the weight, the above-described conventional grass collection box, which is capable of turning for switching between the grass collection posture and the discharge posture, is made up of a support frame as the framework, a bottom plate defining the bottom of the support frame, and a bag made of a net for covering the frame and the bottom plate.
In the conventional structure, the bottom plate of the grass collection box is fixed to the support frame. Therefore, when the support plate strikes against a curb or the ground during the mowing operation or traveling, the external force due to the impact (upward load) acts on the bottom plate or the support frame as it is, whereby the bottom plate or the support frame may be deformed or broken.
It is, therefore, a second object of the present invention to provide a traveling mower which is capable of preventing the grass collection box from deforming or breaking when the bottom plate of the grass collection box strikes against a curb, for example.